Stevens



(No Model.) 2 SheetsShee t 1.

.A. J. ST-EVENS. BALANGEDSLIDE VALVE.

No. 357,424. Patented Feb.8, 1887.

FIG. 1.

(No Model.) 2 She ets- Sheet 2.

7 A. J. STEVENS.

BALANCED SLID -VALVE. No. 357,424., Patented Feb.-8, 1887.

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Q. m aw/{Z 12 a ANDREW J. STEVENS, OF SACRAMENTO, CALIFORNIA.

BALANCED SLIDE-VALVE.

SPECIFICATION forming part of Letters Patent No. 357,424, dated February 8, 1887.

Application filed June 30, 1886. Serial No. 206,751. (No model.)

To ctZZ whom it may concern.-

Be it known that I, ANDREW J. STEvENs, of Sacramento, Sacramento county, State of California, have invented an Improvement in Balanced Slide-Valves; and I hereby declare the following to be a full, clear, and exact description of the same.

My invention relates to certain improvements in balanced slide-valves; and it consists of a valve sliding upon the valve-seat, and having, in addition to the usualsteam-exhaust cavity or cavities, an auxiliary passage pass-' ing through it for steam supply and exhaust purposes, according to the posit-ion of the valve, and in connection with this valve of a shield or balance-plate, and an oval balancering. fitting between the upper side of the valve and the balance-plate, and certain details of construction, all of which willbe more fully described by reference to the accompanying drawings, in which Figure l is a plan view showing the steamchest .with the cover'removed and exposing the valve with its balance-ring. Fig. 2 is a vertical section taken through the plane of the valve-stem and axis of the cylinder. Fig. 3 is a transverse vertical section taken through the center of the valve at right angles with the valve-stem.

A is a steam-chest, and a the steam-chest cover, both being of the ordinary construction.

0 is a section of the cylinder, showing steam and exhaust'ports, as constructed when valves are employed at each end of the cylinder. E is the exhaust-cavity in the valve.

X is the exhaust-passage in the cylinder.

S is the steam port or passage from the steam-chest to the cylinder, and f is an auxiliary passage or passages extending through the body of the valve upon each side of the valve-stein, arching above the exhaust-cavity Ein the valve, and having the ends opening upon each side of the exhaust-cavity through the face of the valve, as shown in Figs. 2 and 3.

D is the valve having an oval groove turned in the back to admit a correspondingly-shaped ring, h, which is let in this groove, the grooved ring being turned by a machine constructed especially for that purpose. cl is a spring of sheet-steel placed under the ring h for the purpose of holding it up in contact with the balance-plate or shield 13. The balance-ring 71. has ajoint made at one end, and the joint 4 piece H fits over the joint to cover the cut and prevent the steam from passing.

The difference between the oval ring herein described and the circular balanced rings heretofore used is, that with a circular packingring you cannot cover the back of a valve that is twice as long as it is wide. It would take two strips to cover the back of such a valve; consequently the expense of making and maintaining would be increased. With a square strip there are four joints on as many separate packing-strips, while with the oval ring the back of any valve may be covered to any desired extent with one ring, no matter what may be its length and width. This cut in the ring allows it to spring together, pressing upon the back of the valve D, and asteamtight joint will be made by the external pressme of the steam,which seeks an outlet in the direction of the small openings 12 n, made through the back of the valve and communicating with the exhaust-cavity E. In the present case'I have shown one of two valves, each valve operating over a steam and exhaust port at one end of the cylinder.

One valve is operated by a hollow stem or sleeve, 0, and the other by a stem, I, which passes through the first one, extending to the valve at the front of the cylinder. These valves are worked independently of each other by any usual or desired mechanism. The shield B inclosesthe valve D,resting upon the valve-seat at each side of the valve, and passing over and entirely coveringit, and the ring it fits steam-tight against the lower side of the shield, thus protecting the back of the valve D from steam-pressure. The auxiliary passage f through the valve D serves to admit steam and to exhaust it from the cylinder inconnection with the other passages.

Fig. 2 shows the valve in such position that steam can exhaust from the cylinder through the passage F, thence through the exhaustcavity E to the exhaust-passage X, and also at the same time through the supplemental passage f to the same discharge X. WVhen the valve is moved to the left so far that steam is admitted to the port S beyond the right end ICQ of the valve, theleft end of the passage F will have passed beyond the edge of the valve-seat suffieiently to admit steam simultaneously and allow it to pass through the passage F and into the port S, steam being thus admitted to the port S from opposite ends of the valve simultaneonsly.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The balance-shield extending horizontally above the slide-valve, having its sides extending down and resting upon the valve-seat at each side of the valve, in combination with the valve having an oval channel cut in its upper surface, an oval ring fitting said channel,with springs beneath to hold it up in contact with the shield, said ring being cut or slotted at one end, and havin gthe cover or joint-piece fitted to the slot to prevent the passage of steam, substantially as herein described.

2. The shield or balanee-plate extending horizontally above the valve within the steamchest, a valve moving upon the valve-seat,

with the exhaust-cavity and supplemental passage made in its'i'ace, and perforations or holes extending through the back and communicating with the exhaust-cavity, in combination with the oval elastic ring fitting a channel in the top of the valve, so as to make A. J. STEVENS.

Vitnesses:

EENJ. 0. SMITH, BERT A. \VoRTHING'roN. 

